Stearidonic acid – much more than a surrogate for EPA

Zooca® Calanus® Oil is unrefined, preserving its full spectrum of fatty acids that goes beyond omega-3. It contains over 40 different fatty acids, providing a diverse and comprehensive nutritional profile, Zooca® Calanus® Oil is rich in essential omega-3 fatty acids, including EPA, DHA and SDA. These fatty acids are renowned for their numerous health benefits.

What is Stearidonic Acid (SDA)?

Stearidonic acid (SDA) is often referred to as the EPA of the plant kingdom and has gained increasing attention as an alternative source of EPA. SDA is converted into EPA, enriching EPA levels as needed from its available SDA pool.

Many plant oils are rich in α-linolenic acid (ALA), but inefficient enzyme systems limit its conversion to EPA. This is where SDA plays a crucial role, bypassing the rate-limiting step involving the enzyme Δ6 desaturase.

The marine oil derived from the zooplankton Calanus finmarchicus combines the best of both the animal and plant kingdoms, having significant content of SDA, EPA and DHA.

The Fate of Dietary Fatty Acids.

Supplemented short- and medium-chain fatty acids are absorbed directly into the bloodstream via intestinal capillaries, while long-chain polyunsaturated fatty acids (LC-PUFAs) are formed into transporter particles entering the bloodstream via lymphatic capillaries.

After a meal, when the blood concentration of fatty acids rises, there is an increase in uptake of fatty acids in different cells of the body, mainly liver cells, adipocytes and muscle cells. The concentration of fatty acids in the blood decreases as the time increase following a meal, which triggers adipocytes to release stored fatty acids into the blood as free fatty acids, in order to supply e.g. muscle cells with energy.

The estimated conversion rate of SDA to EPA in humans is variable and ranges between 20-40%. The variability is dependent on a number of individual factors such as age, gender and background diet.

Omega−6 to Omega−3  Fatty Acid Ratio

Both omega-6 and omega-3 fatty acids are essential, meaning they must be obtained through the diet. Maintaining a healthy balance between these fatty acids is important, with recommended ratios typically around 3:1. Some experts suggest that even a 6:1 ratio (six times more omega-6 than omega-3) can be considered healthy. However, typical Western diets have much higher ratios, often between 10:1 and 30:1, meaning omega-6 intake far exceeds omega-3. Over time, this imbalance leads to excessive incorporation of proinflammatory omega-6 fatty acids into cell membranes, which may have negative health effects

The anti-inflammatory role of SDA

Omega-6 and omega-3 polyunsaturated fatty acids compete for the same metabolic enzymes. As a result, the balance between these fatty acids in the diet strongly influences both the ratio and production rate of eicosanoids—hormones that are involved in the body’s inflammatory and homeostatic processes. Shifting this balance can directly impact the body's inflammatory and metabolic state.

Arachidonic acid (ARA), an omega-6 fatty acid, is an essential structural component of cell membranes.

However, it also promotes inflammation. A diet rich in plant oils over time leads to an increased proportion of ARA in cell membranes compared to omega-3 fatty acids. Since cell membranes are continuously broken down and rebuilt, an excess of omega-6 fatty acids drives inflammatory responses in the body.

This is where stearidonic acid (SDA) plays a key role. Intake of SDA enable the body to have an efficient competitor to ARA in the cell membrane reducing the availability of the pro-inflammatory ARA. Furthermore, SDA effectively competes with ARA for the same metabolic enzymes, helping to regulate eicosanoid production and counteract excessive inflammation.

SDA activator for GLP-1 hormones

Fatty acids are key components of biological lipids. They play essential roles in cell membranes and serve as energy reserves in adipose tissue. In addition to these functions, free fatty acids (FFAs) are now recognized as direct regulators of various physiological processes.

The GPR120 and GPR40 receptors were discovered in 2003, with interest in GPR120 as a drug target emerging in 2005. It was found that this receptor is activated by FFAs, stimulating the release of glucagon-like peptide 1 (GLP-1) and protecting GLP-1-secreting cells. These receptors have since been renamed FFA4 (formerly GPR120) and FFA1 (formerly GPR40).

Regulation of metabolic functions

•Fatty acid sensors (FFA4) at the end of the small intestine

•Responds to long-chain fatty acids

•Stearidonic acid 18:4 n-3 a potent agonist

FFA4 and FFA1 are found on the surface of cells in the intestines, liver, pancreas, and adipose tissue. When activated by FFAs, they promote GLP-1 secretion. Among dietary fatty acids, stearidonic acid (SDA, 18:4 n-3) has been identified as one of the most potent activators of these receptors.

Studies suggest that there appears to be a link between obesity and FFA4, as this receptor is more highly expressed in stomach biopsies from obese patients. Feed supplemented with oil from Calanus oil or exenatide GLP-1 hormone infusion have proven to lower the intra-abdominal fat in obese mouse. Both treatments prevented loss of glucometabolic control which is an additional indication of the potency of SDA in alleviating negative effects in the context of obesity.

References

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• DeFilippis, Andrew P.; Sperling, Laurence S. (March 2006). "Understanding omega-3's". American Heart Journal. 151 (3): 564–570. doi:10.1016/j.ahj.2005.03.051. PMID 16504616. 
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